This section provides background information related to the present disclosure which is not necessarily prior art.
Recent efforts have shown that micro gas turbine engines can be useful in co-generation applications to provide heat and auxiliary electrical power. In particular, the small gas turbine has proven to be light, relatively trouble free and extremely efficient such that it makes an excellent heater. Exemplary embodiments of a co-generator utilizing a micro gas turbine engine are the subject of U.S. Pat. Nos. 6,073,857, 6,161,768 and 6,679,433 by Gordon et al.
These embodiments disclosed by Gordon et al. featured fuel entering the rear housing via a fuel delivery tube; where a minor amount of heat is added. The fuel delivered in the rear housing through drilled holes enters a delivery space between two Belleville springs. Hot air is also introduced at this site, and the fuel-air mixture is fed into the bearing, cooling and lubricating the bearing. Some fuel flows around the bearing flooding the spring suspension system, all the while picking up heat. The mixture then enters a slinger plenum chamber defined by a rotating slinger body and a stationary fuel deflector tube. Additional hot air from the combustion chamber is added before the fuel-air mixture enters the slinger impeller which adds more heat and injects it into the combustion chamber.
With this configuration, fuel delivery is adequate and a blue flame or non-visible flame is produced in the combustion chamber with moderately cold ambient temperatures such as those experienced in the northern states of the continental United States. However, extremely cold ambient temperatures such as those experienced in Canada and Alaska changes the stoichiometry of combustion which presents complication factors. It was known that a fuel heater may be employed to thermally condition the fuel and it was known to insulate the annulus between the combustor and the engine housing to maintain a more consistent operating temperature in the combustion chamber.
During prolonged operation in extreme conditions, it has been observed that carbon deposits can form in the fuel deflector, slinger body and slinger assembly and could not be eliminated. Conventional solutions to this problem were ineffective for eliminating these deposits, eventually leading to blockages in the fuel delivery system. Accordingly, there is a need in the art to provide a fuel delivery system in a mirco gas turbine engine that provides adequate fuel flow and thermal condition without developing excessive carbon deposits resulting in fuel blockage build-up.